The present invention relates generally to the installation of a wiring harness used for interconnecting electrical equipment and/or circuits and, more particularly, to a method and apparatus for dressing or enshrouding such a wiring harness for installation of the harness through an opening of a structural member during manufacture of a product including the structural member. The present invention is particularly applicable to the manufacture of motor vehicles and accordingly will be described with reference to that application.
Wiring harnesses used for motor vehicle electrical circuits are normally preformed as a central bundle of electrical conductors. Projecting from the bundle at varying locations along its length are pigtails, takeouts, connectors, harness hold-downs and the like which may be referred to herein as extensions. The extensions serve to make connections from electrical circuits or equipment to or through the electrical conductors of the wiring harness to associated electrical circuits or equipment or to hold the harness in place in the motor vehicle. Oftentimes, preformed wiring harnesses must be routed through openings in structural members, for example through the firewall of a motor vehicle, to make the required connections. When a wiring harness is to be passed through an opening, the extensions tend to catch on the opening and interfere with quick and easy installation of the harness.
Prior to this time, extensions from a wiring harness typically have been taped against the central bundle or trunk of the wiring harness to facilitate installation. Unfortunately, the application of tape to the individual extensions is a time consuming operation.
An alternate wiring harness dressing arrangement involves the use of tubular "heat shrink" material. The extensions from the wiring harness are held against the harness trunk and a length of tubular heat shrink material is slid over the harness. Heat is then applied to the heat shrink material causing it to shrink or reduce in size and trap the extensions down to substantially the size of the wiring harness trunk. The dressed wiring harness is then inserted through an opening in a motor vehicle firewall or other structural element. Once fully inserted, the shrink wrap material is ripped from the wiring harness to release the extensions for the remainder of the installation of the wiring harness.
Unfortunately, the application of heat shrink material to wiring harnesses requires substantial floor space, the application process is difficult to control, the application requires at least as much labor as taping and the heat shrink material is more expensive than tape. Further, there have been problems in removing the heat shrink material. Perforations have been formed in the heat shrink material to attempt to overcome the removal problem. However, even if perforations are provided, problems may persist since excessive heat can bond the perforated sections together. Of course, there is also the possibility that excesive heat will damage the wiring harnesses.
Accordingly, there is a need for an improved method and apparatus for dressing wiring harnesses for installation through openings in firewalls or other structural elements of motor vehicles and other products.
Preferably the improved wiring harness installation/dressing method and apparatus would utilize inexpensive materials, be readily applied to and removed from wiring harnesses, and permit recycling or reuse of at least some of the apparatus to further reduce the expenses involved in wiring harness installation operations.